1. Field of the Invention
The present invention relates to a switching power-supply module in which switching power-supply circuits, such as inverters or DC-DC converters, are provided on circuit boards.
2. Description of the Related Art
FIG. 8A is a schematic perspective view of one example of a switching power-supply module (e.g., Japanese Unexamined Patent Application Publication No. 2002-58247). In FIG. 8A, reference numeral 1 indicates a switching power-supply module and reference numeral 2 (2A and 2B) indicates circuit boards. Reference numeral 3 indicates electronic components mounted on the circuit boards 2 (2A and 2B). The electronic components 3 and wiring patterns (not shown) define switching power-supply circuits on the circuit boards 2 (2A and 2B).
Reference numeral 4 indicates conductor land patterns, which are provided at edges of the circuit boards 2 (2A and 2B). Reference numeral 5 indicates conductor terminals. As shown in the side view of FIG. 8B, each terminal 5 includes a plurality of clip portions 7 (7A and 7B) and a leg portion 8. The clip portions 7 (7A and 7B) are provided with spacing therebetween in the extending direction of the terminal 5, and the leg portion 8 is arranged so as to extend downward from the portions where the clip portions 7A and 7B are provided. The clip portions 7 (7A and 7B) of the terminals 5 clamp the edges of the formation portions of the conductor land patterns 4 of the circuit boards 2 (2A and 2B), such that the circuit boards 2A and 2B can be stacked with spacing therebetween. That is, the upper portion of each terminal 5, i.e., the portion where the clip portions 7 (7A and 7B) are provided, functions as an interboard-connection portion for interconnecting the corresponding conductor land patterns 4 of the circuit boards 2A and 2B. The tip portions of the leg portions 8 of the terminals 5 can also be connected to a motherboard 10, thereby mounting the circuit boards 2 (2A and 2B) on the motherboard 10.
In addition, at least one of the conductor land patterns 4 provided on each of the circuit boards 2A and 2B is connected to the switching power-supply circuit provided on the circuit board 2. The terminals 5 connect the switching power-supply circuits, provided on the circuit boards 2A and 2B, to an external circuit, provided on the motherboard 10, via the corresponding conductor land patterns 4. That is, the leg portion 8 of each terminal 5 functions as an external-connection portion for connecting the switching power-supply circuits, provided on the circuit boards 2A and 2B, to an external circuit.
For example, the switching power-supply circuit of the circuit board 2A and the switching power-supply circuit of the circuit board 2B have the same circuit configuration. The conductor land pattern 4 connected to an input portion of the switching power-supply circuit of the circuit board 2A and the conductor land pattern 4 connected to an input portion of the switching power-supply circuit of the circuit board 2B are interconnected by the corresponding terminal 5. Similarly, the conductor land pattern 4 connected to an output portion of the switching power-supply circuit of the circuit board 2A and the conductor land pattern 4 connected to an output portion of the switching power-supply circuit of the circuit board 2B are interconnected by the corresponding terminal 5. As a result, the switching power-supply circuit of the circuit board 2A and the switching power-supply circuit of the circuit board 2B are connected in parallel, such that the switching power-supply circuits operate in parallel.
With the switching power-supply module 1 as described above, the circuit boards 2A and 2B on which the switching power-supply circuits are provided are stacked one on the other with spacing therebetween using the terminals 5, such that the switching power-supply circuits on the circuit boards 2A and 2B operate in parallel. This arrangement, for example, increases the output power without increasing an area occupied for the switching power-supply circuits on the motherboard 10.
For example, when the upper limit of an area occupied for the switching power-supply circuits on the motherboard 10 is specified, configuring the switching power-supply module 1 using a plurality of stacked circuit boards increases the circuit-board surface area, as compared to a when only one circuit board is used. An increase in the surface area of the circuit boards facilitates heat dissipation of components mounted on the circuit boards.
Additionally, for example, wherein the switching power-supply module 1 must have an output power of 20 W, when a switching power-supply circuit having an output power of 10 W is already designed, stacking two switching power-supply circuits each having the output power of 10 W provides the switching power-supply module 1 having the required output power of 20 W. This reduces the time and effort required for the design.
In the switching power-supply module 1 shown in FIGS. 8A and 8B, all of the terminals 5 have external connection functions. Thus, this must be considered when designing the circuits of the switching power-supply module 1, and thus, the design freedom of circuit design decreases due to the external connection functions provided for all the terminals 5.
In the manufacturing process of the switching power-supply module 1, after the circuit boards 2A and 2B including the switching power-supply circuits are combined using the terminals 5, the circuit operations of the switching power-supply circuits are inspected for the presence or absence of abnormalities. Thus, not only when both of the switching power-supply circuits are defective but also when one of them is defective and the other is normal, the switching power-supply module 1 is regarded as being defective and is discarded. That is, even a normal switching power-supply circuit may be discarded, which is economically disadvantageous.
In addition, in the inspection process of the switching power-supply module 1, where the switching power-supply module 1 malfunctions and an abnormal portion causing the malfunction is detected, when the abnormal portion is located on, for example, the lower circuit board 2B, it is very difficult to repair the abnormal portion because the lower circuit board 2B is covered by the upper circuit board 2A. Thus, in such a case, the circuit boards 2A and 2B must be disassembled so that the lower circuit board 2B can be repaired, but such a process greatly increases the required time and effort.